1. Field of the Invention
The present invention relates to a process of automatically changing the process order of a plurality of print jobs in response to a situation in an image forming apparatus which can simultaneously receive the print jobs outputted from an external apparatus, for further improving an operating efficiency.
2. Description of the Related Art
Recently there has spread a printing system provided with an image forming apparatus which receives print jobs inputted via a network from an external apparatus such as a personal computer (PC) and executes the output process, and there has been increasing an image forming apparatus which can receive a plurality of print jobs even if the print jobs are simultaneously inputted thereto. There is a problem that in a situation where a plurality of print jobs are inputted to such an image forming apparatus, when the output process is stopped due to occurrence of errors in the middle of output-processing a precedent print job, the output process of the subsequent print job is also stopped. As a method of solving this problem, there is an image forming apparatus provided with a job promoting function (passing printing) in which when an error occurs in the middle of output-processing one print job, the output process is stopped and the subsequent print job is processed to be outputted before the precedent print job (for example, refer to Japanese Patent Laid-Open No. 2004-001320). In the image forming apparatus provided with this job promoting function, in a stage where the error is cleared, the output process of the stopped print job is resumed.
Under such a situation, a wireless network has become widespread. As well known, a wireless communication quality is susceptible to an environment and the network disruption (communication error) tends to occur more easily than a wired network. In addition, in a case where the network disruption occurs in the wireless network, the communication environment itself frequently causes the network disruption and therefore, occurrence of the network disruption is frequently repeated.
FIG. 9 is an image diagram showing the process in a case where the job promoting function as disclosed in Japanese Patent Laid-Open No. 2004-001320 is applied to a printing system for inputting a print job from an external apparatus by using a wireless network.
On the assumption that a job A, a job B and a job C are inputted to a printer in that order from each PC, a rough flow of the process will be explained. First, the printer starts with the output process of the job A first inputted. Before the output process of the job A is completed, the session is disconnected due to the network disruption, and therefore, the printer is automatically promoted to the job B and starts the output process of the job B. When the network of the job A is reconnected (communication is recovered) at a point where the output process of the job B is completed, the printer is not automatically promoted to the output process of the job C and resumes (resumes output of) the development process to the printing process of the precedent job A. When the session disconnection again occurs due to the network disruption before the development process to the printing process of the job A are completed, the printer is automatically promoted to the job C and starts the output process of the job C. After the output process of the job C is completed, the development process to the printing process of the job A is again resumed at a point where the network of the job A is reconnected.
In a case of thus using the wireless network, particularly when the communication is intermittently disconnected or recovered, the automatic promotion tends to easily occur at each time thereof.
In addition, when the automatic promotion frequently occurs, many hours are spent by the time the output processes of all the print jobs are completed, and there occurs an event of keeping a plurality of users waiting for completion of the printing output for a long time.